CS0117 - Xamarin 未检测到“资源”文件夹和文件

我一直在开发一个Xamarin.Forms应用程序，最初是在iOS上，现在是Android上的。我遇到了一个问题，我的代码无法看到我的MainActivity.cs中引用的资源。对于两个不同的资源，我有相同的错误。

我正在学习Udemy课程，讲师强调手动构建一些xml文件，因此有两种类型，axml和xml。

第一个错误

/Users/richardcurteis/Desktop/OneDrive/DevShared/XamarinProjects/NoteTaker/Droid/MainActivity.cs(35,35):
Error CS0117: `NoteTaker.Droid.Resource' does not contain a definition for `Menu' (CS0117) (NoteTaker.Droid)

第二个错误：

/Users/richardcurteis/Desktop/OneDrive/DevShared/XamarinProjects/NoteTaker/Droid/MainActivity.cs(21,21):
Error CS0117: `NoteTaker.Droid.Resource.Id' does not contain a definition for `action_add' (CS0117) (NoteTaker.Droid)

MainActivity.cs

using System;
using Android.App;
using Android.Content;
using Android.Runtime;
using Android.Views;
using Android.Widget;
using Android.OS;
using SupportToolbar = Android.Support.V7.Widget.Toolbar;
using Android.Support.V7.App;
using System.Collections.Generic;
namespace NoteTaker.Droid
{
    [Activity (Label = "Note Taker", MainLauncher = true, Icon = "@drawable/icon")]
    public class MainActivity : AppCompatActivity
    {
        int count = 1;
        private SupportToolbar toolbar;
        protected override void OnCreate (Bundle savedInstanceState)
        {
            Xamarin.Insights.Initialize (XamarinInsights.ApiKey, this);
            base.OnCreate (savedInstanceState);
            new Database ();
            // Set our view from the "main" layout resource
            SetContentView (Resource.Layout.Main);
            toolbar = FindViewById<SupportToolbar> (Resource.Id.toolbar);
            SetSupportActionBar (toolbar);
            // Get our button from the layout resource,
            // and attach an event to it
            Button button = FindViewById<Button> (Resource.Id.myButton);
            button.Click += delegate {
                button.Text = string.Format ("{0} clicks!", count++);
            };
        }
        public override bool OnCreateOptionsMenu (IMenu menu)
        {
            MenuInflater.Inflate (Resource.Menu.addmenu, menu);
            return base.OnCreateOptionsMenu (menu);
        }
        public override bool OnOptionsItemSelected (IMenuItem item)
        {
            switch (item.ItemId)
            {
            case Resource.Id.action_add:
                Console.WriteLine ("Add button clicked");
                return true;
            default:
                return base.OnOptionsItemSelected (item);
            }
        }

    }
}

addmenu.xml 包含action_add id。

<?xml version="1.0" encoding="UTF-8" ?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:app="http://schemas.android.com/apk/res-auto" >
      <item 
        android:id="@+id/action_add"
        android:icon="@drawable/addIcon"
        android:title="Add"
        app:showAsAction="always"
        />
</menu>

Resources树

~/Desktop/OneDrive/DevShared/XamarinProjects/NoteTaker/Droid    
tree Resources/
Resources/
├── AboutResources.txt
├── Resource.designer.cs
├── drawable
│   └── addIcon.png
├── layout
│   ├── Main.axml
│   └── Toolbar.xml
├── menu
│   └── addmenu.xml
├── mipmap-hdpi
│   └── Icon.png
├── mipmap-mdpi
│   └── Icon.png
├── mipmap-xhdpi
│   └── Icon.png
├── mipmap-xxhdpi
│   └── Icon.png
├── mipmap-xxxhdpi
│   └── Icon.png
└── values
    ├── Strings.xml
    └── styles.xml
9 directories, 13 files